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Cicada Killer Wasps: Gentle Giants

Cicada killer wasps look scary, but they are harmless.

Few insects in the Lehigh Valley invoke more terror than cicada killer wasps.  They look like hornets on steroids. Given the right conditions, they can be found in large numbers. Like carpenter bees, the males are not shy about buzzing around humans. If appearances were a guide, the best advice upon seeing a two-inch long cicada killer wasp is to curl up in a little ball and call for help. However, seeing is not believing. Cicada killer wasps are not dangerous, unless you are a cicada or have a rare allergy. Males do not have a stinger and they will never attack. 

Contrary to the information provided by many websites, I believe that female cicada killer wasp stings are not especially painful. In an excellent article on controlling cicada killer wasps, the entomologist and cicada killer wasp expert Joe Coelho describes in vivid detail how he intentionally prodded female cicada killer wasps to sting himself and his graduate students. He evaluated the level of pain for himself and described it as the “tiniest pinprick.” According to Coelho: “After working closely with them since 1991, I have never been stung in the field. Note that I have netted them, put them in vials, dug up their burrows, grabbed them with pliers, and performed other unspeakable acts upon them with impunity. Most people are not interested in becoming that intimate with them.” The article speculates that people who think they were stung by a cicada killer wasp were probably stung by a look-alike European hornet. The fact that cicada killer wasp stings do not hurt very much makes complete sense. The sole purpose of their venom is to paralyze cicadas, not to deter potential predators (like bears) from approaching a nest.

Like carpenter bees and mason bees, cicada killer wasps do not live in hives.  Females build underground burrows up to three feet long and two feet deep.  They provision their larvae in these nests with paralyzed cicadas. The females lay a single egg on one or more paralyzed cicadas, which are then eaten by the cicada wasp larva. The larva then turns into a pupa, spending the winter and spring underground before coming out the next year. We can start to expect seeing cicada killer wasps begin to appear in mid July, around the time that we hear our annual cicadas starting to sing. They typically finish their work by the end of August or early September.

For a cicada, the original sting which knocks out their nervous system is probably more pleasant than being eaten alive. From the wasp’s perspective, fresher is always better, so they have evolved to paralyze their cicadas rather than killing them outright. In a blatantly sexist way, cicada killer wasps provide their daughters with two or three cicadas, while their sons only get one! This is one reason why adult female cicada killer wasps are about twice the size of males. Females are impressive power-lifters, capable of flying around with cicadas that may exceed their own body weight.

A Lehigh Valley connection to cicada killer wasps is that one of the world’s experts on these fascinating insects is Prof. Chuck Holliday at Lafayette College in Easton. He maintains a website that has a wealth of information on the most intimate aspects of the cicada killer wasp lifestyle. If you are interested in learning more about cicada killer wasps, this is a wonderful source of insight gained from years of his personal observations. According to his calculations, a “typical 100-female aggregation can clear 16,606 cicadas from the surrounding trees during the month of August.”

Cicada killer wasps reduce the level of noise generated by annual cicadas. They aerate the lawn with their burrows. They can also deter burglars, solicitors, copper thieves and other unwelcome visitors. I’m sure that I am not the only one who would love to have cicada killer wasps nesting on my property. Nevertheless, there is more information available on how to get rid of them. Go figure. 

Prof. Holliday’s website has some more excellent suggestions for controlling cicada killer wasps. To loosely paraphrase his advice, it is useless and often counter-productive for the homeowner to use insecticides to control cicada killer wasps. If you have an attractive well drained nesting site near a healthy population of cicada-filled trees, they are bound to return every year. Spraying the nesting site with insecticide after the wasps have set up their nests will not stop the next generation of wasps emerging. According to Prof. Holliday, the easiest thing you can do is keep the nesting area wet, since they require a well-drained habitat.  Alternatively, cover the area with crushed stone. For a long term fix, consider landscaping the nesting area with dense vegetation like a mini-prairie, since they require bare soil or very short grass. Lastly, the low-tech badminton racket is a reliable, safe and environmentally sound control method.

This post is contributed by a community member. The views expressed in this blog are those of the author and do not necessarily reflect those of Patch Media Corporation. Everyone is welcome to submit a post to Patch. If you'd like to post a blog, go here to get started.

Pam Ruch June 12, 2012 at 02:00 PM
I was similarly inclined toward being welcoming when cicada killers nested between the steps leading to my garage and a small fish pond. Then they excavated, leaving piles of sandy soil. The steps started sinking and getting to my car became a crazy experience of dodging the fast flying giants, or waiting for an opening and running like hell. When amorous (or hungry?), they buzzed about with complete disregard for other species (meaning me). Being bumped by a wasp that size, even knowing its gentle nature, will get the heart beating. On the other hand, watching one drag a cicada into its cavern was entertaining enough that I stopped everything to watch. I admit to eventually hanging a tennis racket on the fence to help me cross over their territory. And (with apologies) swinging to kill.
Richard Hafner June 12, 2012 at 06:34 PM
I was able to photograph one in action!
Mallory Vough June 12, 2012 at 07:40 PM
I want to say, "Cool!" But I also want to say, "EEP!"
Susan Koomar June 13, 2012 at 08:25 PM
Pretty amazing stuff
Michael Powell July 30, 2012 at 03:40 PM
I suppose the ideal thing would be to compromise: cicada killer wasp proof the areas where you do not want them with the environmentally friendly suggestions provided, while leaving some small piece of favorable habitat available in an out of the way spot for them.

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